Most view consciousness as an emergent property of complex computation mediated by membrane and synaptic processes among brain neurons. But despite ever-increasing detailed knowledge, the brain-as-computer approach has failed to shed light on the nature of consciousness. Accordingly, some now see the brain as a multi-scale hierarchy, resonating inside neurons with deeper, faster (quantum) vibrations in cytoskeletal microtubules, much more like an orchestra than a computer.

In the 19th century a group of gases with diverse chemical structures were found to have a common action. When inhaled, the gases rendered humans and animals immobile, unresponsive and presumably unconscious. When the ‘anesthetic’ gas was exhaled away, the subjects ‘woke up’ and regained consciousness. For each gas, the same concentration was required to anesthetize all types of animals – salamanders, fruit flies, horses, mice and humans, the effective dosage for each gas becoming known as its ‘minimum alveolar concentration’ (‘MAC’), inversely proportional to potency. Anesthetic gases are believed to be stabilized at their targets by weak, quantum interactions known as van der Waals London forces. How do such subtle forces exert profound and selective effects on consciousness?